In a medium bowl, whisk together the milk, cream, sugar and vanilla. Whisk in cake mix and stir until somewhat dissolved. Cover and refrigerate this mixture until very cold (or overnight). Make sure your ice cream maker's insert has been frozen for 24 hours.
Freeze the ice cream mixture in your ice cream maker according to the manufacturer instructions. I have a Kitchenaid and I need to churn it for about 25 minutes.
Scrape the churned ice cream into a freezer-safe container and freeze until firm. Scoop and serve with sprinkles, if desired!